1. Field of the Invention
The present invention relates to a voltage-modulated circuit device, more particularly to a circuit device using the value of a trigger voltage as a predetermined voltage value to trigger an electric conduction, and capable of modulating the voltage on the modulation circuit automatically, such that an electric power supplied to the circuit device is always maintained within a range of required voltage values.
2. Description of Related Art
Zener diode installed on an electronic circuit is generally used for modulating a voltage, and it plays an important role in applications of supplying a power source, like other rectifier diodes. The Zener diode is a P-N junction component made of silicon and differs from other rectifier diodes by its specific selection of using a reverse breakdown area. A breakdown voltage of the Zener diode is generally used in a manufacturing process for controlling a doping level, a diffusion time and an alloy junction temperature carefully to create a desired Zener voltage.
Although the Zener diode can be used for the modulation of a voltage, yet the modulated voltage value is a constant. If it is necessary to adjust the voltage value to a different range, many Zener diodes in different voltage ranges must be manufactured. Therefore, a large number of Zener diodes will be manufactured, particularly when the Zener diodes are purchased, approximately 200,000 pieces of Zener diodes are required for each purchased unit, and many useless ones (such as tens of thousands of them) are left over. Furthermore, the manufacture of Zener diodes requires a precise control of the doping level, diffusion time and alloy junction temperature and incurs a high defective rate, so that it is not easy to manufacture the Zener diodes in compliance with the range of the required voltages. Obviously, the prior art still has drawbacks and requires improvements.